What a guy! Scott Pilkinton I owe you a beer!

http://tech.scottp.net/index.php/2006/09/14/instructions-on-how-to-build-ntop-for-windows-for-the-non-programmer/

This error can occur if the password for the user account that is used for anonymous access in IIS is not synchronized with one of the following passwords:• The password for the user account in Active Directory
• The password for the user account in Local Users and Groups
To synchronize the IIS password with the password that is used in Active Directory or in Local Users and Groups, follow these steps:1. Click Start, click Run, type cmd, and then click OK.
2. Use the cd command to connect to the folder where the Adsutil.vbs file is located. By default, the Adsutil.vbs file is located in the following folder:
drive:\Inetpub\Adminscripts
Note drive is the folder where Windows is installed.
3. At the command prompt, type Cscript adsutil.vbs get w3svc/anonymoususerpass, and then press ENTER. Note the password that is generated.

Note You may have to set the Issecure property in the Adsutil.vbs file to False before you generate a password. To do this, follow these steps:a. In Notepad, open the Adsutil.vbs file.
b. On the Edit menu, click Find, type IsSecureProperty = True, and then click Find Next.
c. Change “IsSecureProperty = True” to “IsSecureProperty = False”.
d. Save the changes, and then close Notepad.

4. Click Start, click Run, type Dsa.msc, and then click OK.

Note If the Web server is a stand-alone server, type Lusrmgr.msc.
5. Expand the domain that you want, and then click Users. If the Web server is a stand-alone server, click Users.
6. Right-click the user account that you want, and then click Reset Password or Set Password.
7. Type the password that you obtained in step 3 two times, and then click OK.

http://support.microsoft.com/kb/909887